1. The Field Of The Invention
The present invention relates in general to multiwall pinch bottom bags, of the type, which are typically fabricated as a tube formed from one or more paper plies.
2. Background Of the Invention
Multiwall bags, fabricated as tubes formed from a plurality of paper plies, are known. Typically, the ends of the tubes are cut, so that when the end or ends of the bag are flattened, the plies of the bag, on both sides of the mouth opening of the bag, are provided with steps. The stepped-end cut pattern creates a closure flap on one side (the "high" side) of the mouth opening of the bag. The side of the bag on the opposite side of the mouth opening is the "short" side. Closure of the bag is typically accomplished by applying adhesive (e.g., hot melt or sonically activatable adhesive) to the outer surface of the short side of the bag. In addition to, or alternative to, providing adhesive on the face of the bag, adhesive may be applied to the inside surface of the closure flap. When the closure flap is folded over the mouth opening of the bag, preferably, the stepped plies of the flap substantially align with and overlie correspondingly cut steps in the bag plies on the face of the bag on the short side of the mouth opening.
Closing the bag by simply folding and adhesively affixing the flap provides the pointed, pinch bottom closure. The opposite end of the bag may be likewise provided with a pinch bottom closure, or it may be closed and sealed in a different configuration, such as a diamond- or rectangular configuration, so that the pinch "bottom" may actually be the top of the bag, as may be found commonly in bags containing dry granular material, like dog food or cat litter.
In addition to having paper plies, one or more plies, typically the innermost one or more plies, may be fabricated from a thin plastic material, or may be coated with a resinous material, to provide a degree of moisture resistance to the finished bag.
While the bag may be formed initially as a simple flattened tube, with folded closure flaps, pinch bottom bags are also known, in which typically both sides of the bag are gusseted, so that there are inward V-folds at each side of the bag, prior to folding the closure flap. Often, because of the stepped-end cutting of the bag plies, in the region of the gussets, the bag material extends beyond the topmost edge of the innermost ply of bag material on the "short" side of the mouth opening, so that in folding over and affixing the closure flap, the tops of the gussets are likewise folded over and captured by the closure flap. Such a prior art gusseted pinch bottom bag is disclosed in Goodrich, U.S. Pat. No. 4,008,850.
When such a bag is closed and sealed, the folded over closure is typically quite strong, and requires cutting of the bag plies, below the folded over and sealed closure, in order to gain access to the contents of the bag.
In order to facilitate opening of such bag structures, multiwall bag structures are known that incorporate tear structures that may be formed by extended perforations, usually in parallel pairs, through one or more plies of the bag, or by providing ripcord structures that are embedded in the bag plies, that lead to pull tabs, that extend to the outer surface of the bag. Such prior art bag opening structures are disclosed in such references as EP 0 596 747 A1; Rodkey, U.S. Pat. No. 3,272,424; Allen, U.S. Pat. No. 2,560,535; Brady et al., U.S. Pat. No. 2,870,955; Vogt, U.S. Pat. No. 4,088,264; Robinson, U.S. Pat. No. 4,557,385; Jacobs, U.S. Pat. No. 4,768,654; Lepisto et al., U.S. Pat. No. 4,483,445; and Thrall, U.S. Pat. No. 5,281,027.
Whether opened by the simple expediency of a cutting or piercing implement, or whether opened through a prior art opening mechanism such as those disclosed in the aforementioned references, typically, opening of the bag either requires substantial effort and/or results in a ragged opening that may include opening the entire mouth of the bag. When the contents of such an opened bag are poured out, because the entire mouth has been opened there is little control over the contents, and undesired spilling of the contents may occur.
It would be desirable to provide a multiwall bag formed from one or more plies of bag material, of which at least the outermost ply or plies is/are formed from paper, that has an easy open feature, to enable facilitated access to the contents of the bag, without requiring the use of a cutting or piercing implement.
It would also be desirable to provide a multiwall bag, such as a pinch bottom closure bag, that is provided with a secure closure, but which is also provided with an easy open feature, which creates a controlled opening of only a portion of the mouth of the bag, for controlled dispensing of the contents of the bag.
These and other desirable features of the present invention will become apparent in light of the present description, claims and drawings.